Duplicate declaration of member '<member name>'
This error arises because a member variable has been declared twice (for example, two Button1s are declared within the code). Note, as well, that declarations must be unique across inherited forms, so that you are not allowed to have a form (for example, Form1) with a member named Button1 declared within it and another form (Form2) that derives from Form1 and also contains a member named Button1. Finally, the names of the members must not be case-sensitive (for example, you may not have two members, okbutton and OKButton).
To correct this error
- Ensure all of your member variables are unique and conform to naming standards of the required language.